Notable changes:
1. Prevent excessive engine module imports.
2. Replace trivial usage of `join()`.
3. Keep the output text sorted whenever possible.
4. Close handles properly.
5. Print error to stderr, not stdout.
6. Report search job exit code.
7. Print exception message to stderr if exception was thrown when
running a search job.
8. Utilize XML library to build XML data
And use 2 spaces as indentation.
PR #21098.
Adds a date column to the built-in search engine to show when a torrent was published/uploaded on the engine site.
When a plugin wants to show a date, it can now add a `pub_date` entry to its result dict. The value format is a unix timestamp (an integer representing seconds since epoch).
Plugins with no date support will keep working.
PR #20703.
Change project directory structure according to application structure.
Change 'nox' configuration option to something more meaningful 'nogui'.
Rename 'Icons' folder to 'icons' (similar to other folders).
Partially add 'nowebui' option support.
Remove QConf project file.
